AUTO-CUT 300 - Victor Technologies
AUTO-CUT 300 - Victor Technologies
AUTO-CUT 300 - Victor Technologies
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3.06 Ground Connections<br />
A. Electromagnetic Interference (EMI)<br />
Pilot arc starting generates a certain amount of electromagnetic interference (EMI), commonly called RF noise.<br />
This RF noise may interfere with other electronic equipment such as CNC controllers, remote controls, height<br />
controllers, etc. To minimize RF interference, follow these grounding procedures when installing mechanized<br />
systems:<br />
B. Grounding<br />
1. The preferred grounding arrangement is a single point or “Star” ground. The single point, usually on the cutting<br />
table, is connected with 1/0 AWG (European 50 mm 2 ) or larger wire to a good earth ground (measuring leass<br />
than 3 ohms; an ideal ground measures 1 ohm or less. Refer to paragraph ‘C’, Creating An Earth Ground. The<br />
ground rod must be placed as close as possible to the cutting table, ideally less than 10 ft (3.0 m), but no more<br />
than 20 ft (6.1 m) from the cutting table.<br />
NOTE<br />
All ground wires should be as short as possible. Long wires will have increased resistance to RF<br />
frequencies. Smaller diameter wire has increased resistance to RF frequencies, so using a larger<br />
diameter wire is better.<br />
2. Grounding for components mounted on the cutting table (CNC controllers, height controllers, plasma remote<br />
controls, etc.) should follow the manufacturer’s recommendations for wire size, type, and connection point<br />
locations.<br />
For Thermal Dynamics components (except Arc Starter and Gas Control Module) it is recommended to use a<br />
minimum of 10 AWG (European 6 mm 2 ) wire or flat copper braid with cross section equal to or greater than 10<br />
AWG connected to the cutting table frame. The Remote Arc Starter uses 1/0 earth ground wire and the Gas<br />
Control Module should use minimum # 4 AWG wire. The connection point must be to clean bare metal; rust and<br />
paint make poor connections. For all components, wires larger than the recommended minimum can be used<br />
and may improve noise protection.<br />
3. The cutting machine frame is then connected to the “Star” point using 1/0 AWG (European 50 mm 2 ) or larger<br />
wire.<br />
4. The plasma power supply work cable (see NOTE) is connected to the cutting table at the single point “Star” ground.<br />
NOTE<br />
Do Not connect the work cable directly to the ground rod.<br />
5. Make sure work cable and ground cables are properly connected. The work cable must have a solid connection<br />
to the cutting table. The work and ground connections must be free from rust, dirt, grease, oil and paint. If<br />
necessary grind or sand down to bare metal. Use lock washers to keep the connections tight. Using electrical<br />
joint compound to prevent corrosion is also recommended.<br />
6. The plasma power supply chassis is connected to the power distribution system ground as required by electrical<br />
codes. If the plasma supply is close to the cutting table (see NOTE) a second ground rod is not usually<br />
needed, in fact it could be detrimental as it can set up ground loop currents that cause interference.<br />
When the plasma power supply is far away from the ground rod and interference is experienced, it may help to<br />
install a second earth ground rod next to the plasma power supply. The plasma power supply chassis would<br />
then be connected to this ground rod.<br />
NOTE<br />
It is recommended that the Plasma Power Supply be within 20 - 30 ft (6.1 – 9.1 m) of the cutting table,<br />
if possible.<br />
7. The plasma control cable should be shielded with the shield connected only at the cutting machine end.<br />
Connecting the shield at both ends will allow ground loop currents which may cause more interference than with<br />
no shield at all.<br />
Manual No. 0-4817 Auto-Cut <strong>300</strong> 3-10 INSTALLATION